• the risk of fracture is far from negligible when performing a mandibular prosthesis combined with a flexible material, as it is done at the expense of hard resin, especially in the incisal area. It is therefore desirable to strengthen the base with a metal casting This interface does not affect the aesthetics or comfort and can proceed further in a reline without difficulty (Fig. 32 and 33)

• stains can be the result of eating habits, making Medicis, techniques, inadequate hygiene or sometimes the flexible material itself: it is preferable to avoid using in these cases, acrylic resins (flexible) that appear less stable over time than lesautres materials

• bacterial colonization of soft bases is the biggest criticism of these materials. As in other disciplines (periodontics, implantology ...), patients who received this type of prosthetic treatment are subject to maintenance "mandatory", with regular checkups. They are aware of oral hygiene techniques to make prosthetic.

For all these reasons it is reasonable to advocate the use of these bases for a flexible medium term.

Oral hygiene prosthetic

Hygiene and prosthetic control are essential to maintaining the biocompatibility of implants. Hygiene procedure must be adapted to the nature of flexible bases and the practitioner must ensure that it is controlled by the patient.

Fig. 30 - Surface of Permlastic (Kerr) (x 20).

Fig. 32 - Large bar renfort.Hygiène oral

- Daily brushing bearing surfaces with a soft brush;

- This simple but effective method can be completed once a week by rinsing (2 min) with a solution of chlorhexidine gluconate 0.2%;

- However, antiseptic mouth rinses should be used with caution as they may alter the delicate balance of the oral environment.

hygiene prosthetic

Daily cleaning of the prosthesis is performed using a soft toothbrush or surgery (to remove as little as possible the underside) and soapy water or added to toothpaste. The detergent solutions are typically too aggressive for the prosthetic material and are not a satisfactory alternative to mechanical cleaning. The daily disinfection with chlorhexidine implants is only possible in cases of acute infections. Wearing night is not recommended if the patient does not have a prosthetic strict oral hygiene.

Fig. 31 - Surface texture more grainy pulp SS White (x 20).

Fig. 33 - metal interface.

maintenance prosthetic

Control sessions, the practitioner carefully cleans the denture with a brush and appropriate curettes and then immersed in a few minutes cuveultrasonique (minimum power: 100 W). Disinfection of the prosthesis is provided by an antiseptic solution containing benzalkonium chloride (1 / 700) [6].

Prevention of candidiasis

Certain clinical situations lead us to sail patients who may be exposed to Candida infection. This risk is increased in the case of flexible bases, because the proliferation of microorganisms (particularly yeasts) on the surface of this material is higher than that observed on hard bases [7]. Patients at risk are therefore subject to an ongoing clinical monitoring:

• regular measurement of salivary pH, using indicators colored paper, is a diagnostic and a condition index of saliva. A significant decrease in pH will sign a breeding ground for yeast growth;

• possibly mycological examination is performed with a removal and direct observation by light microscopy (staining or Gram-May-GunwaldGiem) or culture in the laboratory for analysis.

The cons-indications

Material characteristics and constraints on their use does not solve all problems. There are cons-specific guidance:

• the asialie: often resulting in cancer treatment. Yet these are generally patients where the risk of osteoradionecrosis are important and which require rehabilitation with a flexible base. The practitioner will choose, if possible, a compromise using saliva substitutes. Over the years, often there is a small salivary secretion ... saving;

• Poor hygiene may be the result of a motor disability or cerebral, but also neglect. The motivation for health and / or supported by a third party (family caregivers) can sometimes afford to undertake the completion of prosthetic treatment;

• candidiasis: they should be treated, if possible, before the completion of the prosthesis and close monitoring should be ensured;

• in maxillofacial prosthesis: flexible materials should never be in contact with the tissues Mobile (veil) or sinuses and nasal mucous membranes;

• floating peaks can be addressed through these soft materials "permanent".

Therefore, it is essential to emphasize the importance of oral hygiene prosthetic, monitoring and maintenance "The patient must be" informed "principally made aspects of this type of prosthetic treatment.

conclusion

One can not ignore the fact that flexible bases are part intégrantede our armamentarium. They are often the only prosthetic solution for patients with anatomical defects and / or functional such that no surgery is possible. The indications for the use of flexible basis (regardless of the family of materials) show that the compromises are not an easy solution. Indeed, these materials can not in any way mitigate or compensate for an inadequate technique. On the other hand, the chemical nature of flexible bases, their surface, their binding to the rigid base, the aging phenomena ... are parameters that not only can not tolerate certain clinical situations, but we are now booking their use in the medium term.

The patient will be clearly informed of the benefits but also the limits of this type of prosthetic restoration as well as constraints related to hygiene and maintenance. Only under these conditions that the patient and practitioner will find satisfaction in the realization of a complete denture lined with a flexible so-called "permanent".

perspectives

The bases do not fit soft tissue Mobile, which has two consequences:

1) they provide a peripheral seal of poor quality;

2) their use is limited in maxillofacial prosthetics.

We think it may be possible in future to improve their surface, but especially our research continues to use sector-based flexible. It was planned that the flexible material to areas requiring damping while keeping a peripheral seal rigid resin. ■

bibliographie

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T. In vitro analysis of Candida albicans adherenceto soft denture lining materials. J Prosthet Dent 1992;68:804-808.